Hi Daniel, thanks for the input.
I don’t think the discussion about fly selection is a discussion about the best way to catch fish. Obviously many different approaches work. Fly selection is more a discussion about the personality and philosophy of the fisherman; the choice reflects what one finds fun and challenging about the sport.
For many, learning the insects, observing what the trout eat, choosing a fly that’s just right for the season, place, time of day and type of river is a big part of the sport. I admire this skill. For others who have a desire to simplify, catching fish with a single pattern is more satisfying. This approach is one of relying on skill and presentation instead of "blaming the fly". I admire this, too. As a saxophone player, I often scoff at those players that switch mouthpieces every 3 months to improve their sound--stick with one and learn how to use it!
I know this goes against your advice (and my own advice, apparently), but for next season I've decided to stock my fly box with at least one of each major fly pattern in at least 2 sizes: caddis, stonefly, mayfly, attractor, midge, and nymphs (some bead head, some not). I’ll probably throw in some misc stuff like a crayfish imitation, and a sneaky Pete for smallmouth. I’ve been enjoying reading and learning about all the classic fly patterns and I want to try them out. I don't feel I can make an informed decision until I do this. And, I have to admit, part of this approach comes from discovering after 10 years in the same house that I have an Orvis store just 3 minutes away. I’m a kid in a candy store right now.
Will all these flies help me catch more fish than someone with a single type of fly? Who knows. Unless you fish both styles side-by-side there will never be a control for the experiment. And I’m not sure the answer matters that much in the bigger picture.